This invention relates to systems for supplying supplemental oxygen to a patient intermittently with the supply on for a predetermined number of ON respiratory cycles and the supply off for a predetermined number of OFF respiratory cycles. Oxygen saving is further enhanced by shutting the oxygen flow off during the exhalation phase of each ON respiratory cycle.
The incidence of chronic obstructive lung disease (C.O.L.D.) is increasing. These patients have inadequate pulmonary gas exchange resulting in inadequate oxygenation of blood passing through the lungs. Inadequate blood oxygenation and consequent body tissue hypoxia account for the disabling effects of the disease. It has been demonstrated that continuous administration of supplemental oxygen by nasal cannula overcomes the functional disability and greatly improves the quality of life as well as prolonging life. It is now common practice for ambulatory patients to carry an oxygen supply weighing nine pounds and lasting 3-4 hours. Prior art devices conserve oxygen by shutting off the gas flow during the exhalation phase of each respiratory cycle, which may double the effective supply.